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SubjectRe: [PATCH 19/19] HID: multitouch: Remove the redundant touch state
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Hello Henrik,

On Sun, Aug 12, 2012 at 11:42 PM, Henrik Rydberg <rydberg@euromail.se> wrote:
> With the input_mt_sync_frame() function in place, there is no longer
> any need to keep the full touch state in the driver. This patch
> removes the slot state and replaces the lookup code with the input-mt
> equivalent. The initialization code is moved to mt_input_configured(),
> to make sure the full HID report has been seen.

This patch seems to be a little bit complex.
It has very good things, but also many things that hinders the readability.

And you should also remove the /* touchscreen emulation */ things in
mt_input_mapping as input_mt_init_slots handles now the init of ABS_X
ABS_Y and ABS_PRESSURE.

>
> Cc: Benjamin Tissoires <benjamin.tissoires@enac.fr>
> Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
> ---
> drivers/hid/hid-multitouch.c | 162 ++++++++++++++++++-------------------------
> 1 file changed, 66 insertions(+), 96 deletions(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index b15133c..bd4bc3c 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -52,13 +52,6 @@ MODULE_LICENSE("GPL");
> #define MT_QUIRK_VALID_IS_CONFIDENCE (1 << 6)
> #define MT_QUIRK_SLOT_IS_CONTACTID_MINUS_ONE (1 << 8)
>
> -struct mt_slot {
> - __s32 x, y, p, w, h;
> - __s32 contactid; /* the device ContactID assigned to this slot */
> - bool touch_state; /* is the touch valid? */
> - bool seen_in_this_frame;/* has this slot been updated */
> -};

Why removing this struct?
Removing it infers a lot of unneeded changes in the patch.

As the mt_sync_frame handle the quirk NOT_SEEN_MEANS_UP, we should
just remove the field seen_in_this_frame.

> -
> struct mt_class {
> __s32 name; /* MT_CLS */
> __s32 quirks;
> @@ -76,7 +69,6 @@ struct mt_fields {
> };
>
> struct mt_device {
> - struct mt_slot curdata; /* placeholder of incoming data */
> struct mt_class mtclass; /* our mt device class */
> struct mt_fields *fields; /* temporary placeholder for storing the
> multitouch fields */
> @@ -93,7 +85,9 @@ struct mt_device {
> * 1 means we should use a serial protocol
> * > 1 means hybrid (multitouch) protocol */
> bool curvalid; /* is the current contact valid? */
> - struct mt_slot *slots;
> + __s32 x, y, p, w, h;
> + __s32 contactid; /* the device ContactID assigned to this slot */
> + bool touch_state; /* is the touch valid? */

Again, by keeping the first field, you don't lose any memory and
things are packed and organized!
(having x, y, etc... at the root of the device struct is kind of weird...)

> };
>
> /* classes of device behavior */
> @@ -128,31 +122,12 @@ struct mt_device {
>
> static int cypress_compute_slot(struct mt_device *td)
> {
> - if (td->curdata.contactid != 0 || td->num_received == 0)
> - return td->curdata.contactid;
> + if (td->contactid != 0 || td->num_received == 0)
> + return td->contactid;

This patch contains many unneeded modifications of this type.... :-(

> else
> return -1;
> }
>
> -static int find_slot_from_contactid(struct mt_device *td)
> -{
> - int i;
> - for (i = 0; i < td->maxcontacts; ++i) {
> - if (td->slots[i].contactid == td->curdata.contactid &&
> - td->slots[i].touch_state)
> - return i;
> - }
> - for (i = 0; i < td->maxcontacts; ++i) {
> - if (!td->slots[i].seen_in_this_frame &&
> - !td->slots[i].touch_state)
> - return i;
> - }
> - /* should not occurs. If this happens that means
> - * that the device sent more touches that it says
> - * in the report descriptor. It is ignored then. */
> - return -1;
> -}
> -

I'm always happy to remove code.... ;-)

> static struct mt_class mt_classes[] = {
> { .name = MT_CLS_DEFAULT,
> .quirks = MT_QUIRK_NOT_SEEN_MEANS_UP },
> @@ -390,7 +365,6 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> case HID_DG_CONTACTID:
> if (!td->maxcontacts)
> td->maxcontacts = MT_DEFAULT_MAXCONTACT;
> - input_mt_init_slots(hi->input, td->maxcontacts, 0);

this thing was worrying me, so it's better this way.

> mt_store_field(usage, td, hi);
> td->last_field_index = field->index;
> td->touches_by_report++;
> @@ -464,12 +438,31 @@ static int mt_input_mapped(struct hid_device *hdev, struct hid_input *hi,
> return -1;
> }
>
> -static int mt_compute_slot(struct mt_device *td)
> +static void mt_input_configured(struct hid_device *hdev, struct hid_input *hi)
> +
> +{
> + struct mt_device *td = hid_get_drvdata(hdev);
> + struct mt_class *cls = &td->mtclass;
> + struct input_dev *input = hi->input;
> + unsigned int flags = 0;
> +
> + if (test_bit(INPUT_PROP_POINTER, input->propbit))
> + flags |= INPUT_MT_POINTER;
> + if (test_bit(INPUT_PROP_DIRECT, input->propbit))
> + flags |= INPUT_MT_DIRECT;

These two tests are really strange: the function input_mt_init_slots
already sets those bits....
Maybe we should handle INPUT_PROP_POINTER, INPUT_PROP_DIRECT by
keeping the flag instead of setting the bits and re-read them to
finally re-set them...

And yes, I know that input_mt_init_slots does a lot more than just
setting those two bits, but it's the impression I feel when reading
this.

Anyway, besides this things, I'm happy with the input_configured callback.

> +
> + if (cls->quirks & MT_QUIRK_NOT_SEEN_MEANS_UP)
> + flags |= INPUT_MT_DROP_UNUSED;
> +
> + input_mt_init_slots(input, td->maxcontacts, flags);
> +}
> +
> +static int mt_compute_slot(struct mt_device *td, struct input_dev *input)
> {
> __s32 quirks = td->mtclass.quirks;
>
> if (quirks & MT_QUIRK_SLOT_IS_CONTACTID)
> - return td->curdata.contactid;
> + return td->contactid;
>
> if (quirks & MT_QUIRK_CYPRESS)
> return cypress_compute_slot(td);
> @@ -478,25 +471,43 @@ static int mt_compute_slot(struct mt_device *td)
> return td->num_received;
>
> if (quirks & MT_QUIRK_SLOT_IS_CONTACTID_MINUS_ONE)
> - return td->curdata.contactid - 1;
> + return td->contactid - 1;
>
> - return find_slot_from_contactid(td);
> + return input_mt_assign_slot_by_id(input, td->contactid);
> }
>
> /*
> * this function is called when a whole contact has been processed,
> * so that it can assign it to a slot and store the data there
> */
> -static void mt_complete_slot(struct mt_device *td)
> +static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
> {
> - td->curdata.seen_in_this_frame = true;
> - if (td->curvalid) {
> - int slotnum = mt_compute_slot(td);
> + int slot;
>
> - if (slotnum >= 0 && slotnum < td->maxcontacts)
> - td->slots[slotnum] = td->curdata;
> - }
> td->num_received++;
> + if (!td->curvalid)
> + return;
> +
> + slot = mt_compute_slot(td, input);
> + if (slot < 0 || slot >= td->maxcontacts)
> + return;
> +
> + input_mt_slot(input, slot);
> + input_mt_report_slot_state(input, MT_TOOL_FINGER, td->touch_state);
> + if (td->touch_state) {
> + /* this finger is on the screen */
> + int wide = (td->w > td->h);
> + /* divided by two to match visual scale of touch */
> + int major = max(td->w, td->h) >> 1;
> + int minor = min(td->w, td->h) >> 1;
> +
> + input_event(input, EV_ABS, ABS_MT_POSITION_X, td->x);
> + input_event(input, EV_ABS, ABS_MT_POSITION_Y, td->y);
> + input_event(input, EV_ABS, ABS_MT_ORIENTATION, wide);
> + input_event(input, EV_ABS, ABS_MT_PRESSURE, td->p);
> + input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
> + input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
> + }
> }
>
>
> @@ -504,52 +515,20 @@ static void mt_complete_slot(struct mt_device *td)
> * this function is called when a whole packet has been received and processed,
> * so that it can decide what to send to the input layer.
> */
> -static void mt_emit_event(struct mt_device *td, struct input_dev *input)
> +static void mt_sync_frame(struct mt_device *td, struct input_dev *input)
> {
> - int i;
> -
> - for (i = 0; i < td->maxcontacts; ++i) {
> - struct mt_slot *s = &(td->slots[i]);
> - if ((td->mtclass.quirks & MT_QUIRK_NOT_SEEN_MEANS_UP) &&
> - !s->seen_in_this_frame) {
> - s->touch_state = false;
> - }
> -
> - input_mt_slot(input, i);
> - input_mt_report_slot_state(input, MT_TOOL_FINGER,
> - s->touch_state);
> - if (s->touch_state) {
> - /* this finger is on the screen */
> - int wide = (s->w > s->h);
> - /* divided by two to match visual scale of touch */
> - int major = max(s->w, s->h) >> 1;
> - int minor = min(s->w, s->h) >> 1;
> -
> - input_event(input, EV_ABS, ABS_MT_POSITION_X, s->x);
> - input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);
> - input_event(input, EV_ABS, ABS_MT_ORIENTATION, wide);
> - input_event(input, EV_ABS, ABS_MT_PRESSURE, s->p);
> - input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
> - input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
> - }
> - s->seen_in_this_frame = false;
> -
> - }
> -
> - input_mt_report_pointer_emulation(input, true);
> + input_mt_sync_frame(input);
> input_sync(input);
> td->num_received = 0;
> }
>
> -
> -
> static int mt_event(struct hid_device *hid, struct hid_field *field,
> struct hid_usage *usage, __s32 value)
> {
> struct mt_device *td = hid_get_drvdata(hid);
> __s32 quirks = td->mtclass.quirks;
>
> - if (hid->claimed & HID_CLAIMED_INPUT && td->slots) {
> + if (hid->claimed & HID_CLAIMED_INPUT) {

the "td->slots" test was ugly ;-)

Thanks,
Benjamin

> switch (usage->hid) {
> case HID_DG_INRANGE:
> if (quirks & MT_QUIRK_ALWAYS_VALID)
> @@ -560,29 +539,29 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
> case HID_DG_TIPSWITCH:
> if (quirks & MT_QUIRK_NOT_SEEN_MEANS_UP)
> td->curvalid = value;
> - td->curdata.touch_state = value;
> + td->touch_state = value;
> break;
> case HID_DG_CONFIDENCE:
> if (quirks & MT_QUIRK_VALID_IS_CONFIDENCE)
> td->curvalid = value;
> break;
> case HID_DG_CONTACTID:
> - td->curdata.contactid = value;
> + td->contactid = value;
> break;
> case HID_DG_TIPPRESSURE:
> - td->curdata.p = value;
> + td->p = value;
> break;
> case HID_GD_X:
> - td->curdata.x = value;
> + td->x = value;
> break;
> case HID_GD_Y:
> - td->curdata.y = value;
> + td->y = value;
> break;
> case HID_DG_WIDTH:
> - td->curdata.w = value;
> + td->w = value;
> break;
> case HID_DG_HEIGHT:
> - td->curdata.h = value;
> + td->h = value;
> break;
> case HID_DG_CONTACTCOUNT:
> /*
> @@ -602,11 +581,11 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
> }
>
> if (usage->hid == td->last_slot_field)
> - mt_complete_slot(td);
> + mt_complete_slot(td, field->hidinput->input);
>
> if (field->index == td->last_field_index
> && td->num_received >= td->num_expected)
> - mt_emit_event(td, field->hidinput->input);
> + mt_sync_frame(td, field->hidinput->input);
>
> }
>
> @@ -733,15 +712,6 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
> if (id->vendor == HID_ANY_ID && id->product == HID_ANY_ID)
> mt_post_parse_default_settings(td);
>
> - td->slots = kzalloc(td->maxcontacts * sizeof(struct mt_slot),
> - GFP_KERNEL);
> - if (!td->slots) {
> - dev_err(&hdev->dev, "cannot allocate multitouch slots\n");
> - hid_hw_stop(hdev);
> - ret = -ENOMEM;
> - goto fail;
> - }
> -
> ret = sysfs_create_group(&hdev->dev.kobj, &mt_attribute_group);
>
> mt_set_maxcontacts(hdev);
> @@ -772,7 +742,6 @@ static void mt_remove(struct hid_device *hdev)
> struct mt_device *td = hid_get_drvdata(hdev);
> sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
> hid_hw_stop(hdev);
> - kfree(td->slots);
> kfree(td);
> hid_set_drvdata(hdev, NULL);
> }
> @@ -1085,6 +1054,7 @@ static struct hid_driver mt_driver = {
> .remove = mt_remove,
> .input_mapping = mt_input_mapping,
> .input_mapped = mt_input_mapped,
> + .input_configured = mt_input_configured,
> .feature_mapping = mt_feature_mapping,
> .usage_table = mt_grabbed_usages,
> .event = mt_event,
> --
> 1.7.11.4
>
> --
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